Search for Second Occurence of Substing and get containing text

danj35 has asked for the wisdom of the Perl Monks concerning the following question:

Hi all,

At the moment I've been able to retrieve a paragraph of text from a variable by specifying a start and an end point as so:

if(Dumper($page) =~ /===Comments===(.*?)=Microarray Data=/s) {  
            $lit_comments = $1; 
        }
[download]

By doing this I've stored all the text under the ===Comments=== header. E.g.

===Comments===

Comments made here will be stored in $lit_comments.

=Microarray Data=

Now I have a problem where I need to do the same again, except this time I need to extract the text after the second occurrence of the ===Comments=== tag. Any ideas anyone?

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Re: Search for Second Occurence of Substing and get containing text by BrowserUk (Patriarch) on May 06, 2010 at 15:32 UTC
m//g in a while loop will continue from where it left off last time: `$s = "head\nstuff\nstuff\ntail\nthis\nthat\nhead\nother stuff\nmore\n +tail\nand more";; while( $s =~ m[head\n(.+?)tail\n]smg ) { print ">$1<"; };; >stuff stuff < >other stuff more <` [download]	[reply] [d/l]
Re: Search for Second Occurence of Substing and get containing text by kennethk (Abbot) on May 06, 2010 at 15:23 UTC
There are some very clever ways to do this, but simple is probably easiest: why not just include the string `===Comments===` in your regular expression twice? `if(Dumper($page) =~ /===Comments===(.?)=Microarray Data=/s.?===Comme +nts===(.*)) { $lit_comments = $1; $second_comments = $2; }` [download] See perlretut for some reference material.	[reply] [d/l] [select]
Re: Search for Second Occurence of Substing and get containing text by graff (Chancellor) on May 06, 2010 at 21:56 UTC
The previous replies probably give enough to go on, but the OP question wasn't clear. To expand a bit, one of the following two methods would be useful, depending on what the question really meant: Read more... (723 Bytes) The basic point is that a regex match will return its capture(s) as a list, which you can then pick from via an array slice (or assign to an array or list).	[reply] [d/l]
Re: Search for Second Occurence of Substing and get containing text by k_manimuthu (Monk) on May 07, 2010 at 06:03 UTC
For your code `if(Dumper($page) =~ /===Comments===(.?)=Microarray Data=/s) { $lit_comments = $1; }` [download] Search the match one time only You want to do the stuff's repeated. You will use the while loop and use the 'g' (global modifier) in your code. `while(Dumper($page) =~ /===Comments===(.?)=Microarray Data=/gs) { $lit_comments = $1; }` [download] Otherwise. Try this `Dumper($page) =~ s/===Comments===(.*?)=Microarray Data=/&my_process($& +)/ges; sub my_process { my ($content)=@_; ## Do You stuff's Here return $content; }` [download]	[reply] [d/l] [select]